We manufactures an array of standard and custom non-invasive air-in-line sensors and bubble detectors to fit your needs. Our proprietary digital “smart” circuits can be calibrated to detect bubbles in almost any fluid and tubing material.

Featured Scales

Scales for applications like rugged medical reagent/waste with overload protection from side loads, tension and compression. Typical specialized requirements include small sizes, high temperature, low capacities, “Cenelec” dielectric, and overload protection.

Featured Custom Solutions

The majority of SMD products are custom designed sensors, meeting the more specialized needs of OEMs. Strain Measurement Devices’ unrivaled engineering team supports product design, shortens development cycles, and provides production engineered solutions for unique requirements and aggressive cost targets.

From Our Blog

Fluid Management Sensors Strain Measurement Devices is known for our state of the art Load Cell technology, but our engineers have been designing an ever expanding sensor portfolio that monitors, measures and controls fluid. Fluid management sensors are a diverse …

Fluid rate measurement can be done a number of ways. The method used typically depends on the fluid material that needs to be monitored. Measuring flow in tubes can be done through the use of various flow meter types including, …

Strain Measurement Devices is dedicated to development and research ensuring continuous improvements to our sensors and manufacturing processes. The company's engineering and development staff supports product design, shorten development cycles, and provide production-engineered solutions.

Recent News

“Medical Technology brings you the latest news and insights from the medical device industry in a stunning, interactive format, supported by market analysis and data from research specialist GlobalData. Published bi-monthly and free to read on all devices, this digital magazine …

Bubble Sensors – Test Pin

SMD Bubble Sensors have an optional test pin that is often required for medical device applications. On our standard sensors, the last digit of the part number denotes whether the test pin is enabled or disabled:

“E-Type” sensors (e.g. A430-SLTE) have the test function enabled.

“D-Type” sensors (e.g. A430-SLTD) have the test function disabled.

If the test function is enabled, the test pin (typically white wire) must be grounded for normal operation. Pulling the test pin to 5VDC internally disables the transmitter portion of the circuit while the test pin is high.

If the transmitter is disabled, you should expect to see an “air” output under all circumstances – if you see a 5V output while the test pin is pulled high then there is something wrong with the circuit. The sensor is not detecting bubbles while the test pin is high so if you’re checking the test pin during device operation, ideally you should only pull the test pin high for a short amount of time (for example 1 to 2 50 microsecond cycles).

Do not apply more than 5VDC to the test pin of any bubble sensor, regardless of the input voltage of the sensor.